Engine starter drive



June 26 1934. C JUNK 1,964,666

ENGINE STARTER DRIVE Filed June 9. 1930 EEKEL lull. Q51 [6 INVENTOR ATTORNEYS Patented June 26, 1934 UNITED STATES 1,964,666 ENGINE STARTER DRIVE Carl Junk, Detroit, Mich., assignor to Victor A. C. Koch, Detroit, Mich.

Application June 9, 1930, Serial No. 459,891

2 Claims.

This invention relates to devices for automatically connecting a starting motor with an internal combustion engine, and its object is to provide means for the purpose which will operate 5 effectually and automatically when the starting motor is started, to effect a driving connection Without shock and to prevent stalling of the starting motor, said connection being arranged to provide a yielding of such connection. It is also 1 an object to provide a simplified construction which is cheap to manufacture and which will operate automatically to effect a disconnection immediately upon the starting of the engine.

With the above and other ends in view, the invention consists in providing a spring arranged to serve as a screw-thread for moving a driving member into and out of driving connection and also as yieldable connecting means between starting motor and driving member, and in providing certain other new and novel features of con-- struction and arrangement, all as hereinafter set forth and more particularly pointed out in the appended claims, reference being had to the accompanying drawing in which- Figure 1 is a sectional detail illustrative of an arrangement of starting motor and engine fly wheel with a driving connection illustrative of the present invention in elevation, and in connection with a driving pinion which is shown in section and out of driving position;

Fig. 2 is a bottom view of Fig. 1 and showing the driving pinion in driving position;

Fig. 3 is a view of Figs. 1 and 2 looking toward the end of the starting motor shaft and driving pinion thereon;

Fig. 4 is a sectional detail of a driving pinion with a spring member shown therein in elevation; and

Fig. 5 is a small diagrammatic view showing in end elevation, an internal combustion engine to which the invention is shown as applied.

As illustrative of a common arrangement for starting an internal combustion engine, an 45 engine 1 is illustrated in Fig. 5 as having a fly wheel casing 2 in which the engine fly wheel 3 is housed, said fly wheel being provided with the usual external gear teeth 4 to be engaged by a driving pinion 5 mounted upon the shaft 6 of 50 an electric starting motor indicated as a whole by the numeral 7, and which starting motor casing 8 is rigidly secured endwise to a lateral extension 9 of the casing 2 with its shaft 6 extending across and beyond the face of the fly wheel. 55 The present invention relates to the means by and manner in which the driving pinion 5 is connected to the shaft 6, this means comprising a spring 10 coiled about the shaft and secured at one end adjacent the end of the shaft by means of a screw or pin 11 passing through 69; an eye 12 formed at the end of the spring into an opening in the shaft. This spring is preferably of rectangular form in cross-section with its free end adjacent a bearing for the shaft or preferably, engaging a shoulder 13 formed on the shaft 6 where it projects through the wall of the casing 9. This spring, therefore turns with the shaft but is free to be compressed endwise on the shaft, the turns of the spring being spaced apart in simulation of a thread of long pitch.

Thepinion 5 is formed with a plain straight bore of a diameter to receive the spring 10 and slide freely thereon, said pinion having the usual external teeth 14 to engage the teeth 4 on the fly wheel 3, the rear corners 15 of these teeth 14 be- '15; ing rounded off so that when said pinion is moved endwise on the shaft 6 into engagement with said teeth on the fly wheel, these teeth will readily intermesh, and to serve as a thread within the bore of this pinion, a short spring 16 of similar size and form in cross section to the spring 10 is secured within said bore by means of a pin or stud 17 on one end of said spring engaging an opening in the pinion adjacent the end of the pinion which is toward the shoulder 13 or inner end of the shaft, the opposite end of said short spring being unconnected to the pinion or shaft. The width of the space between the coils of the spring 10 is preferably greater than the width of the coils of the spring 16 and therefore there is a 0,- short free turning movement of the pinion relative to the shaft before these springs come into contact, and when they do contact each is free to yield in the direction of its length due to such difference in the width of the space between the turns of spring 10 and. the width of the turns of spring 16 and that said springs are secured at one end only.

When the parts are at rest and it is desired to start the engine 1, the electric motor 7 is started, ITO-0 rapidly rotating its shaft 6 and as the pinion 5 is loosely mounted on said shaft with its internal spring thread 16 in mesh with the coils of the spring 10, the shaft thread spring 10 will be screwed into the pinion due to the fact that said pinion turns freely upon the shaft and will tend to lag behind the rotation of the shaft due to the fact said pinion is unbalanced, it having an extension 18 at one side. As soon as the pinion is moved a short distance by such screw-thread spring connection, it will come into engagement with the teeth 4 on the fly wheel, which will further retard it and it will be forced into mesh with said fly wheel teeth by the screw action of the spring 10. At this time, the fly wheel is at rest and will offer a very sudden and strong resistance to the rotation of said pinion. Were it not for the free yielding action of the springs 10 and 16 or either of them, longitudinally of the shaft, the motor 7 would be subjected to a severe shock due to this sudden application of load and might be stalled, but said pinion may rotate a short distance against the resistance oifered in compressing said springs, due to this longitudinal yield of said springs and the space between the turns of the two springs. The shock of sudden application of load is thus relieved and the torque of the electric motor applied more gradually, giving said motor time in which to increase its torque sufliciently to start the engine.

As long as the speed of the shaft and pinion are greater than the travel of the fly wheel, power will continue to be applied to turn the wheel but immediately upon the starting of the engine under its own power so that the fly wheel travels faster than the pinion, the action of the screwsprings will be reversed and the pinion will be moved by this screw action, out of engagement with the fly wheel.

The operation of throwing the pinion into and out of mesh with the fly wheel is therefore automatic and the springs 10 and 16 or either of them, serve the double purpose of acting as a screw connection of the pinion to its shaft and of providing a yielding enagement or connection to prevent shocks and stalling of starting motor.

Obviously changes in the particular construction and arrangement of the parts may be made within the scope of the appended claims and such changes are contemplated.

Having thus fully described my invention, what I claim is:

1. In an engine starter drive, the combination with the shaft of a starting motor and a toothed member to be driven thereby, of means for transmitting motion from said shaft to said toothed member comprising a pinion having a plain bore, a coiled spring member sleeved upon said shaft and extending substantially throughout the length thereof, with one end secured thereto adjacentthe free end of said shaft and its opposite end free, said pinion being sleeved upon said spring member for movement longitudinally of said shaft into and out of mesh with said toothed member upon relative rotation of said pinion and member, and a second coiled spring member sleeved upon said shaft within the bore of said pinion and secured at one end only to said pinion with its free end extending toward the secured end of the first mentioned spring and with its turns lying between the turns of said first spring, both of said springs being adapted to yield longitudinally when said pinion comes into contact with said toothed member.

2. In an engine starter drive, the combination of means for transmitting motion from the shaft of a starting motor to the fly wheel of an engine and comprising a pinion, a spring member coiled about the starting motor shaft and over which said pinion is sleeved to move longitudinally of said shaft into and out of mesh with teeth upon said fly wheel, means for securing one end only of said spring to said shaft adjacent the free end thereof and extending the length of said shaft, and a short spring member of a length substantially equal to that of said pinion with its turns intermeshing with the turns of said spring memto permit free limited relative movement of said springs longitudinally of said shaft and free limited movement of said pinion longitudinally of said shaft.

CARL JUNK.

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